diff --git a/content/blog/new-release-12-jul-2026.mdx b/content/blog/new-release-12-jul-2026.mdx new file mode 100644 index 0000000..cfe2fd2 --- /dev/null +++ b/content/blog/new-release-12-jul-2026.mdx @@ -0,0 +1,88 @@ +--- +title: Mist 0.4.0 is released, virtual methods, array types, and more +author: Klesti Selimaj +date: 2026-07-12 +--- + +## New Features + +### Virtual Methods + +The `virtual` keyword enables polymorphic dispatch through vtables. Methods marked `virtual` can be overridden in subclasses and will be dispatched dynamically at runtime: + +```mist +pub class Animal +{ + pub virtual void speak(&self) + { + println!("..."); + } +} + +class Dog : Animal +{ + void speak(&self) override + { + println!("Woof!"); + } +} +``` + +### Array Types + +Fixed-size array types are now supported with `[T; N]` syntax: + +```mist +[i32; 10] numbers; // Array of 10 i32s +[str&; 3] names; // Array of 3 string references +``` + +### Tuple Variable Declarations + +Tuple variables can now be declared with explicit type annotations using `as`: + +```mist +(i32, bool) as x, y = (1, true); + +i32 a, b = (1, 2, 3); +``` + +### Include Directives + +C-style include directives for importing external files and crates: + +```mist +#include // Global include +pub use my_crate::module; // Use include +#include "local.mist" // Local include +``` + +## Syntax Changes + +### Allman Style Struct/Enum Fields + +Struct and enum fields now use semicolons instead of commas: + +```mist +// Before (v0.3.x) +struct Point { i32 x, i32 y } + +// After (v0.4.0) +struct Point { i32 x; i32 y; } +``` + +## Bug Fixes + +- Fixed default initializers in classes +- Fixed the mapping system for error remapping +- Fixed include manifest path resolution +- Fixed various analyzer bugs +- Fixed the publish command +- Fixed completion pollution in LSP + +## Improvements + +- Updated bootstrap infrastructure +- Migrated to core library for `c_void` and classes +- Removed unnecessary lifetime annotations +- Fixed generics and function type handling \ No newline at end of file diff --git a/content/docs/guide/classes.mdx b/content/docs/guide/classes.mdx index 79c8bbb..3012991 100644 --- a/content/docs/guide/classes.mdx +++ b/content/docs/guide/classes.mdx @@ -103,113 +103,6 @@ class Circle } ``` -### Under the Hood +--- -A class `Dog : Animal` generates: - -1. A Rust struct with a `_super: Animal` field (or `_vptr: &'static [*const c_void]` for root classes) -2. A vtable constant with function pointers for each public method -3. An `impl` block with `Deref` and `DerefMut` -4. Method trampolines (`__m_`) that are dispatched through the vtable -5. A `new()` constructor that initializes via `MaybeUninit` and calls the user's `constructor(&mut self)` - -The vtable is unified: parent entries are copied, overridden entries replace parent slots, and new methods are appended. - -### Safety - -Classes use `MaybeUninit::zeroed().assume_init()` inside the generated `new()` function — an inherently unsafe operation. This raises a natural question: **Are class constructors unsafe?** - -The answer is **no**. The compiler statically verifies that every field is initialized before the constructor returns, eliminating the undefined behavior that raw `MaybeUninit` would normally carry. - -#### Static Field Initialization Verification - -When a class has a constructor, the semantic checker (`check_class_semantics`) collects every declared field and walks the constructor body to prove each one is written to: - -1. **Direct assignment tracking** — Expressions like `self.field = value` are recognized as mutations of `field`. The analyzer checks for `=` and `->` operators whose left-hand side is a `self.field` path. - -2. **`&mut self.field` tracking** — Taking a mutable reference to a field (`&mut self.field`) also counts as initializing it, since the reference can only be taken if the field is being set up. - -3. **Transitive method calls** — If the constructor calls `self.helper()`, the analyzer follows into `helper`'s body and tracks which fields *it* initializes. This transitively propagates through nested calls: - -```mist -class Player -{ - str& name; - i32 health; - - pub constructor(str& name) - { - self.name = name; - self.setup_health(); - } - - void setup_health(&mut self) - { - self.health = 100; // Counts toward constructor's verification - } -} -``` - -4. **Branch intersection** — For `if`/`else`, `match`, and loops, fields must be initialized in **all** branches. If one branch initializes `x` but another does not, `x` is considered uninitialized. This ensures soundness regardless of the runtime path: - -```mist -pub constructor(bool flag) -{ - if flag { - self.health = 100; - } else { - self.health = 0; - } - // Both branches init health ✓ -} -``` - -5. **Super initialization** — When a class inherits, the `_super` field is added to the required-field list. Any assignment to `super` counts: - -```mist -pub constructor(str& name) -{ - super = Super::new(name); -} -``` - -If any field is uninitialized after the full analysis, a compile-time error is reported with the field's exact source location: - -``` -class field `Player.health` is uninitialized -``` - -#### Override Validation at Compile Time - -When a method uses the `override` keyword, the codegen emits a hidden test function that verifies the Deref chain at compile time: - -```rust -#[allow(invalid_value)] -fn __test_vt() { - let this: &Self = &unsafe { std::mem::MaybeUninit::::zeroed().assume_init() }; - let _: &Target = this; // Forces compiler to check Deref -} -``` - -This ensures `&Self` can always deref into the base class type. If the inheritance hierarchy is invalid, the Rust compiler rejects it. - -#### VTable Safety - -The `_vptr` (vtable pointer) is set *twice* during construction: - -1. **Before** the constructor body runs — enabling virtual dispatch inside the constructor itself -2. **After** the constructor body — in case a base-class constructor ran and overwrote the pointer - -This ensures that virtual method calls work correctly even during object construction, without exposing uninitialized memory through the vtable. - -#### Summary - -| Risk | Mitigation | -|------|-----------| -| Uninitialized fields via `MaybeUninit` | Static field-initialization verification rejects incomplete constructors | -| UB from reading uninitialized fields | Intersection analysis ensures all branches init the same fields | -| Invalid override signatures | Compile-time Deref test validates the inheritance chain | -| Vtable corruption during construction | `_vptr` is set before and after the constructor body | -| Unsafe code in generated constructors | `#[allow(invalid_value)]` is scoped to the generated `new()` only | - -The `MaybeUninit` pattern is an implementation detail of the generated code — the Mist compiler proves soundness at the language level, so the user's constructor body is safe Mist code with no manual `unsafe` annotations required. +For details on how classes are compiled — vtable layout, constructor codegen, and safety verification — see [Class Internals](/docs/internals/classes). diff --git a/content/docs/guide/variables.mdx b/content/docs/guide/variables.mdx index d1ebdbf..12cbe6c 100644 --- a/content/docs/guide/variables.mdx +++ b/content/docs/guide/variables.mdx @@ -28,7 +28,7 @@ let [= ]; Tuple variables can be declared with explicit type annotations using `as`: ```mist -(i32, bool) (x, y) as = (1, true); +(i32, bool) as x, y = (1, true); i32 a, b = (1, 2, 3); ``` diff --git a/content/docs/internals/classes.mdx b/content/docs/internals/classes.mdx new file mode 100644 index 0000000..eb312e9 --- /dev/null +++ b/content/docs/internals/classes.mdx @@ -0,0 +1,118 @@ +--- +title: Class Internals +description: How classes are compiled under the hood — vtable layout, code generation, and safety verification. +icon: Shield +--- + +This page covers the implementation details of Mist classes. You don't need to read this to use classes — it's here for curiosity and compiler contributors. + +### Under the Hood + +A class `Dog : Animal` generates: + +1. A Rust struct with a `_super: Animal` field (or `_vptr: &'static [*const c_void]` for root classes) +2. A vtable constant with function pointers for each public method +3. An `impl` block with `Deref` and `DerefMut` +4. Method trampolines (`__m_`) that are dispatched through the vtable +5. A `new()` constructor that initializes via `MaybeUninit` and calls the user's `constructor(&mut self)` + +The vtable is unified: parent entries are copied, overridden entries replace parent slots, and new methods are appended. + +### Safety + +Classes use `MaybeUninit::zeroed().assume_init()` inside the generated `new()` function — an inherently unsafe operation. This raises a natural question: **Are class constructors unsafe?** + +The answer is **no**. The compiler statically verifies that every field is initialized before the constructor returns, eliminating the undefined behavior that raw `MaybeUninit` would normally carry. + +#### Static Field Initialization Verification + +When a class has a constructor, the semantic checker (`check_class_semantics`) collects every declared field and walks the constructor body to prove each one is written to: + +1. **Direct assignment tracking** — Expressions like `self.field = value` are recognized as mutations of `field`. The analyzer checks for `=` and `->` operators whose left-hand side is a `self.field` path. + +2. **`&mut self.field` tracking** — Taking a mutable reference to a field (`&mut self.field`) also counts as initializing it, since the reference can only be taken if the field is being set up. + +3. **Transitive method calls** — If the constructor calls `self.helper()`, the analyzer follows into `helper`'s body and tracks which fields *it* initializes. This transitively propagates through nested calls: + +```mist +class Player +{ + str& name; + i32 health; + + pub constructor(str& name) + { + self.name = name; + self.setup_health(); + } + + void setup_health(&mut self) + { + self.health = 100; // Counts toward constructor's verification + } +} +``` + +4. **Branch intersection** — For `if`/`else`, `match`, and loops, fields must be initialized in **all** branches. If one branch initializes `x` but another does not, `x` is considered uninitialized. This ensures soundness regardless of the runtime path: + +```mist +pub constructor(bool flag) +{ + if flag { + self.health = 100; + } else { + self.health = 0; + } + // Both branches init health ✓ +} +``` + +5. **Super initialization** — When a class inherits, the `_super` field is added to the required-field list. Any assignment to `super` counts: + +```mist +pub constructor(str& name) +{ + super = Super::new(name); +} +``` + +If any field is uninitialized after the full analysis, a compile-time error is reported with the field's exact source location: + +``` +class field `Player.health` is uninitialized +``` + +#### Override Validation at Compile Time + +When a method uses the `override` keyword, the codegen emits a hidden test function that verifies the Deref chain at compile time: + +```rust +#[allow(invalid_value)] +fn __test_vt() { + let this: &Self = &unsafe { std::mem::MaybeUninit::::zeroed().assume_init() }; + let _: &Target = this; // Forces compiler to check Deref +} +``` + +This ensures `&Self` can always deref into the base class type. If the inheritance hierarchy is invalid, the Rust compiler rejects it. + +#### VTable Safety + +The `_vptr` (vtable pointer) is set *twice* during construction: + +1. **Before** the constructor body runs — enabling virtual dispatch inside the constructor itself +2. **After** the constructor body — in case a base-class constructor ran and overwrote the pointer + +This ensures that virtual method calls work correctly even during object construction, without exposing uninitialized memory through the vtable. + +#### Summary + +| Risk | Mitigation | +|------|-----------| +| Uninitialized fields via `MaybeUninit` | Static field-initialization verification rejects incomplete constructors | +| UB from reading uninitialized fields | Intersection analysis ensures all branches init the same fields | +| Invalid override signatures | Compile-time Deref test validates the inheritance chain | +| Vtable corruption during construction | `_vptr` is set before and after the constructor body | +| Unsafe code in generated constructors | `#[allow(invalid_value)]` is scoped to the generated `new()` only | + +The `MaybeUninit` pattern is an implementation detail of the generated code — the Mist compiler proves soundness at the language level, so the user's constructor body is safe Mist code with no manual `unsafe` annotations required. diff --git a/content/docs/meta.json b/content/docs/meta.json index b70c4ff..399a75d 100644 --- a/content/docs/meta.json +++ b/content/docs/meta.json @@ -22,6 +22,7 @@ "internals/architecture", "internals/parsing", "internals/semantic-analysis", + "internals/classes", "internals/codegen", "internals/transpiler", "internals/builder",